Weston invented and patented the saturated cadmium cell in 1893.[3] The cathode in the cell is an amalgam of cadmium with mercury. The anode is of pure mercury, and the electrolyte is a solution of cadmium sulphate. The Weston cell is a wet-chemical cell that produces a highly stable voltage suitable as a laboratory standard for calibration of voltmeters. The temperature coefficient was reduced by shifting to an unsaturated design, the predominant type today.[2] When the Weston cell became the International Standard for EMF in 1911, Weston waived his patent rights.